pi.c

用于底层开发的TCPIP协议栈源代码

#include <time.h>
#include <stdio.h>
#include <dos.h>
#include <bios.h>
#include "global.h"
#include "mbuf.h"
#include "iface.h"
#include "pktdrvr.h"
#include "netuser.h"
#include "pi.h"
#include "z8530.h"
#include "ax25.h"
#include "trace.h"
#include "nospc.h"

#include "session.h"
#include "lapb.h"
#include "proc.h"
#include "ip.h"
#include "devparam.h"

#ifndef FP_OFF
#define FP_OFF(fp)	((unsigned)(fp))
#endif
#ifndef FP_SEG
#define FP_SEG(fp)	((unsigned)((unsigned long)(fp) >> 16))
#endif

void b_rxint(struct pichan *);
void b_txint(struct pichan *);
void b_exint(struct pichan *);
void a_rxint(struct pichan *);
void a_txint(struct pichan *);
void a_exint(struct pichan *);

static void xwrite_scc(struct pichan *hp,uint16 ctl,uint16 reg,
	uint16 val );
static char xread_scc(struct pichan *hp, uint16 ctl, char reg);
static int32 pi_ctl(struct iface *iface,int cmd,int set,int32 val);
static int pi_raw(struct iface *iface,struct mbuf **bpp);
static int pi_stop(struct iface *iface);
static void rts(struct pichan *hp, uint16 x);
void setup_rx_dma(struct pichan *hp);
void setup_tx_dma(struct pichan *hp);
static void set_acc_delay(void);
static void tdelay(register struct pichan *hp,unsigned int time);
static int scc_init(register struct pichan *hp);

static struct PITAB Pi[PIMAX];	/* Device table - one entry per card */
static INTERRUPT (*pihandle[])() = {	/* handler interrupt vector table */
	pi0vec,
	pi1vec,
	pi2vec
};
static uint16 Page_regs[] = {
	0x87,0x83,0x81,0x82,0,0x8b,0x89,0x8a
};
static struct pichan Pichan[2*PIMAX];	/* channel table - 2 entries per card */
static uint16 pinbr;

extern uint16 acc_delay;	/* Delay for the 8530 chip access recovery time */


/* This calculates the constant to be used in the delay loops
 *  which satify the SCC's access recovery time.  It needs to be timed and
 *  calculated because a fixed value would not work in a 4.77mhz XT
 *  to a 40mhz 486 (and beyond).
 */
static void
set_acc_delay()
{	
	long starttime, endtime;
	int n;
	int ticks;

	starttime = bioscnt();
	for(n = 0; n < 10; n++)
		mloop();
	endtime = bioscnt();
	ticks = (int) (endtime - starttime);
	if(ticks == 0)
		ticks = 1;
	acc_delay = 61/ticks;
	if(acc_delay == 0)
		acc_delay = 1;
	fflush(stdout);
}

/* Write 8530 register */
static void
xwrite_scc(hp,ctl,reg,val)
register struct pichan *hp;
register uint16 ctl;
uint16 reg,val;
{
	wrtscc(hp->cardbase,ctl,reg,val);
}

/* Read 8530 register */
static char
xread_scc(hp,ctl,reg)
register struct pichan *hp;
register uint16 ctl;
char reg;
{
	return(rdscc(hp->cardbase,ctl,reg));
}

/* Setup 8253 chip for time delay */
static void
tdelay(hp,time)
register struct pichan *hp;
unsigned int time;		 /* Time to delay in milliseconds */
{
	int n,port;
	unsigned int t1;
	unsigned char sc;

	if(hp->base & 2){ /* If A channel */
		sc = SC1;
		t1 = time;
		port = hp->cardbase+TMR1;
	} else {
		sc = SC2;
		t1 = 10 * time; /* 10s of milliseconds for the B channel */
		port = hp->cardbase+TMR2;
	}

	/* Setup timer sc */
	outportb(hp->cardbase+TMRCMD, sc|LSB_MSB|MODE0);
	
	/* satisfy access time restriction */
	for(n=0; n<5;n++)
		;
	/* times 2 to make millisecs */
	outportb(port, (t1 << 1) & 0xFF);

	/* satisfy access time restriction */
	for(n=0; n<5;n++)
		;
	outportb(port, (t1 >> 7) & 0xFF);

	/* Enable correct int for timeout */
	xwrite_scc(hp,hp->base+CTL,R15,CTSIE);
	xwrite_scc(hp,hp->base+CTL,R1,EXT_INT_ENAB);
	xwrite_scc(hp,hp->base+CTL,R0,RES_EXT_INT);
}

/* Master interrupt handler.  One interrupt at a time is handled.
 * here. Service routines are called from here.
 */
INTERRUPT (far *(piint)(dev))()
int dev;
{
	register char st;
	register uint16 pcbase;
	struct pichan *hp;
	struct PITAB *pip;

	pip = &Pi[dev];
	pip->ints++;
	pcbase = pip->addr;

	/* Read interrupt status register (only valid from channel A)
	 * Process all pending interrupts in while loop
	 */
	hp = &Pichan[2 * dev];	/* Assume channel A */
	while((st = xread_scc(hp,pcbase+CHANA+CTL,R3)) != 0){
		if(st & CHARxIP){
			/* Channel A Rcv Interrupt Pending */
			hp = &Pichan[2 * dev];
			a_rxint(hp);
		} else if(st & CHATxIP){
			/* Channel A Transmit Int Pending */
			hp = &Pichan[2 * dev];
			a_txint(hp);
		} else if(st & CHAEXT){
			/* Channel A External Status Int */
			hp = &Pichan[2 * dev];
			a_exint(hp);
		} else if(st & CHBRxIP){
			/* Channel B Rcv Interrupt Pending */
			hp = &Pichan[(2 * dev)+1];
			b_rxint(hp);
		} else if(st & CHBTxIP){
			/* Channel B Transmit Int Pending */
			hp = &Pichan[(2 * dev)+1];
			b_txint(hp);
		} else if(st & CHBEXT){
			/* Channel B External Status Int */
			hp = &Pichan[(2 * dev)+1];
			b_exint(hp);
		}
		/* Reset highest interrupt under service */
		xwrite_scc(hp,hp->base+CTL,R0,RES_H_IUS);
	} /* End of while loop on int processing */
	return pip->chain ? pip->oldvec : NULL;
}

static void
a_exint(hp)
register struct pichan *hp;
{
	register uint16 cmd;
	char st;
	int32 t,ca;
	struct mbuf *bp;
	int i_state;

	i_state = dirps();

	st = xread_scc(hp,hp->base+CTL,R0);     /* Fetch status */

	/* reset external status latch */
	xwrite_scc(hp,CTL+hp->base,R0,RES_EXT_INT);
	cmd = hp->base+CTL;
	hp->exints++;

	if((hp->rstate >= ACTIVE) && (st & BRK_ABRT)){	
		setup_rx_dma(hp);
		hp->rstate = ACTIVE;
	}
	switch(hp->tstate){
	case ACTIVE:
		hp->tstate = FLAGOUT;
		tdelay(hp,hp->squeldelay);
		break;
	case FLAGOUT:
		if((bp = dequeue(&hp->sndq)) == NULL){
			/* Nothing to send - return to receive mode */
			hp->tstate = IDLE;
			rts(hp,OFF);
			restore(i_state);
			return;
		}
		/* Get all chars */
		hp->txcnt = pullup(&bp,hp->sndbuf,hp->bufsiz);
		free_p(&bp);	/* Truncate overly long packets */

		/* NOTE - fall through if more to send */
	case ST_TXDELAY:
		/* Disable DMA chan */
		outportb(DMA_MASK, DMA_DISABLE|hp->dmachan);

		/* Set up for TX dma */
		xwrite_scc(hp,cmd,R1,WT_FN_RDYFN|EXT_INT_ENAB);

		/* Setup DMA controller for tx */
		setup_tx_dma(hp);

		/* select transmit interrupts to enable */
		/* Allow DMA on chan */
		outportb(DMA_MASK,DMA_ENABLE|hp->dmachan);

		/* reset CRC, Txint pend*/
		xwrite_scc(hp,cmd,R0,RES_Tx_CRC|RES_Tx_P);

		/* allow Underrun int only */
		xwrite_scc(hp,cmd,R15,TxUIE);

		/* Enable TX DMA */
		xwrite_scc(hp,cmd,R1,WT_RDY_ENAB|WT_FN_RDYFN|EXT_INT_ENAB);

		/* Send CRC on underrun */
		xwrite_scc(hp,cmd,R0,RES_EOM_L);

		/* packet going out now */
		hp->tstate = ACTIVE;
		break;
	case DEFER:
		/* we have deferred prev xmit attempt
		 * See Intel Microcommunications Handbook, p2-308
		 */
		xwrite_scc(hp,cmd,R0,RES_EXT_INT);
		xwrite_scc(hp,cmd,R0,RES_EXT_INT);
		if((xread_scc(hp,cmd,R0) & DCD) != 0){
			hp->tstate = DEFER;
			tdelay(hp,100);
			/* Defer until dcd transition or 100mS timeout */
			xwrite_scc(hp,CTL+hp->base,R15,CTSIE|DCDIE);
			restore(i_state);
			return;
		}
		/* Defer logic. Wait until deftime is in the past (so we
		 * defer to any overheard CTS messages) AND the p-persistence
		 * dice roll succeeds. The computation of ca allows for clock
		 * rollover (which happens every 49+ days).
		 */
		t = msclock();
		ca = hp->deftime - t;
		if(ca > 0){
			hp->tstate = DEFER;
			tdelay(hp,ca);
			restore(i_state);
			return;
		}
		hp->deftime = t;	/* Keep from getting too old */
		if((rand() & 0xff) > hp->persist){
			hp->tstate = DEFER;
			tdelay(hp,hp->slotime);
			restore(i_state);
			return;
		}
		/* Assert RTS early minimize collision window */
		xwrite_scc(hp,cmd,R5,TxCRC_ENAB|RTS|Tx8);
		rts(hp,ON);	/* Transmitter on */
		hp->tstate = ST_TXDELAY;
		tdelay(hp,hp->txdelay);
		restore(i_state);
		return;
	} /* switch(hp->tstate) */

	restore(i_state);
} /* a_exint() */

/* Receive interrupt handler for the A channel 
 */
static void
a_rxint(hp)
register struct pichan *hp;
{
	register uint16 cmd;
	register uint16 bytecount;
	char rse;
	struct mbuf *bp;
	int i_state;
	
	hp->rxints++;
	cmd = hp->base+CTL;

	i_state = dirps();
	rse = xread_scc(hp,cmd,R1); /* Get special condition bits from R1 */
	if(rse & Rx_OVR){
		/* If receiver overrun */
		hp->rovers++;
		hp->rstate = RXERROR;
	}

	if(rse & END_FR){
		/* If end of frame */
		/* figure length of frame from 8237 */
		outportb(DMA_RESETFF,0); /* reset firstlast ff */
		bytecount = inportb(DMABASE+2*hp->dmachan+1);
		bytecount += inportb(DMABASE+2*hp->dmachan+1) << 8;
		bytecount = hp->bufsiz - 1 - bytecount;

		if((rse & CRC_ERR)||(hp->rstate > ACTIVE)||(bytecount < 10)){
			if((bytecount >= 10) && (rse & CRC_ERR))
				hp->crcerr++; /* Ignore noise */

			/* Reset buffer pointers */
			hp->rstate = ACTIVE;
			setup_rx_dma(hp);
		} else {
			/* Here we have a valid frame. Copy to buffer,
			 * minus 2 CRC bytes
			 */
			bytecount -= 2;
			if((bp = alloc_mbuf(bytecount+sizeof(struct iface *)))
			 != NULL){
				bp->data += sizeof(struct iface *);
				bp->cnt = bytecount;
				memcpy(bp->data,hp->rcvbuf,bytecount);
				net_route(hp->iface,&bp);
				hp->rxcnt = 0;
				hp->rxframes++;
			}
			/* packet queued - get buffer for next frame */
			setup_rx_dma(hp);
		} /* end good frame queued */
	} /* end EOF check */

	xwrite_scc(hp,hp->base+CTL,R0,ERR_RES);	/* error reset */
	restore(i_state);
}

void
a_txint(hp)
register struct pichan *hp;
{
	register uint16 cmd;
	int32 t,ca;
	struct mbuf *bp;
	int i_state;

	cmd = CTL+hp->base;

	i_state = dirps();
	switch(hp->tstate){
	case IDLE:
		/* Transmitter idle. Find a frame for transmission */
		if((bp = dequeue(&hp->sndq)) == NULL){
			rts(hp,OFF);
			restore(i_state);
			return;
		}
		/* If a buffer to send, we drop thru here */
		hp->txcnt = pullup(&bp,hp->sndbuf,hp->bufsiz);
		free_p(&bp);	/* Truncate overly long packet */
		hp->tcp = hp->sndbuf;
	case DEFER:
		/* we may have deferred prev xmit attempt */
		/* Check DCD - debounce it
		 * See Intel Microcommunications Handbook, p2-308
		 */
		xwrite_scc(hp,cmd,R0,RES_EXT_INT);
		xwrite_scc(hp,cmd,R0,RES_EXT_INT);
		if((xread_scc(hp,cmd,R0) & DCD) != 0){
			hp->tstate = DEFER;
			tdelay(hp,100);
			/* defer until DCD transition or timeout */
			xwrite_scc(hp,cmd,R15,CTSIE|DCDIE);
			restore(i_state);
			return;
		}
		/* Defer logic. Wait until deftime is in the past (so we
		 * defer to any overheard CTS messages) AND the p-persistence
		 * dice roll succeeds. The computation of ca allows for clock
		 * rollover (which happens every 49+ days).
		 */
		t = msclock();
		ca = hp->deftime - t;
		if(ca > 0){
			hp->tstate = DEFER;
			tdelay(hp,ca);
			restore(i_state);
			return;
		}
		hp->deftime = t;	/* Keep from getting too old */
		if((rand() & 0xff) > hp->persist){
			hp->tstate = DEFER;
			tdelay(hp,hp->slotime);
			restore(i_state);
			return;
		}

		/* Assert RTS early minimize collision window */
		xwrite_scc(hp,cmd,R5,TxCRC_ENAB|RTS|Tx8);
		rts(hp,ON);	/* Transmitter on */
		hp->tstate = ST_TXDELAY;
		tdelay(hp,hp->txdelay);
		restore(i_state);
		return;
	default:
		break;
	} /* end switch(hp->state) */

	restore(i_state);
} /*a_txint */

static void
b_rxint(hp)
register struct pichan *hp;
{
	register uint16 cmd;
	char rse;
	struct mbuf *bp;
	int i_state;

	hp->rxints++;
	cmd = CTL+hp->base;

	i_state = dirps();
	if((xread_scc(hp,cmd,R0)) & Rx_CH_AV){
		/* there is a char to be stored
		 * read special condition bits before reading the data char
		 */
		rse = xread_scc(hp,cmd,R1); /* get status byte from R1 */
		if(rse & Rx_OVR){
			/* Rx overrun - toss buffer */
			/* reset buffer pointers */
			hp->rcp = hp->rcvbuf;